Add I dimension start and end information for the write group tasks

[junwang-noaa]

Description

Add i dimension start and end index information for the tasks in a write group. This information can be used by the UPP 2D decomposition test.

Solution

Set up the lon_start_wrtgrp and lon_end_wrtgrp array with the lon start and end information.

Alternatives

If applicable, add a description of any alternative solutions or features you've considered.

Testing:

1. Have you tested the code changes? On what platforms?
   Tested on hera.
2. Have you run regression test in ufs-weather-model or ufs-s2s-model with code changes?

• Will the baseline results change?
• If yes, please give brief explanation of your code updates on the regression test.

Dependent PRs:

Directly reference any issues or PRs in this or other repositories that this is related to, and describe how they are related. Example:

• associated ufs-weather-model/pull/<pr_number>